Currently, multiple central processing units (CPU) in a server are connected to a same bus, and processor nodes (namely, the CPUs) each are connected to one cache. When working, a cache node (namely, the Cache) connected to each processor node that needs to process first data in service processing mirrors the first data in a memory device, and caches the mirrored first data into each cache node. If the first data cached by other cache nodes is not modified in time after the first data cached by a cache node is updated by a processor node, cache coherence cannot be achieved. There are roughly two specific causes of incoherence of the cached first data. For one thing, a processor node modifies the first data in a cache node, but the first data cached in other cache nodes is not modified accordingly. For another, after modifying the first data in a cache node during execution of a service process, a processor node does not write back the modified first data to the memory device in time; and/or while modifying the first data cached in other cache nodes accordingly, a processor node migrates the service process between processor nodes at the same time, and consequently unmodified first data is incorrectly invoked in the migrated service process, causing incorrect execution of the service processing.
Broadcasting of a data request and bus arbitration on the data request are used in bus snooping protocols (for example, the Modified, Shared or Invalid (MSI) protocol, the Modified, Exclusive, Shared or Invalid (MESI) protocol, and the Modified, Owned, Exclusive, Shared or Invalid (MOESI) protocol) in the prior art, and can resolve a cache coherence problem on multiple cache nodes mounted to a same bus. However, in terms of sending a data request, the bus snooping protocol depends on complete sequentiality of a shared bus, and only one processor can occupy the bus at each moment, resulting in a relatively long communication delay and relatively poor extensibility. In addition, during updating of a cache status, the snooping protocol uses a system-wide broadcasting manner, resulting in excessively high bus communication load and high power consumption. Moreover, a snooping-based protocol is inapplicable to a message network because the message network is unordered and cannot ensure sequentiality and an atomic operation of the similar bus. In addition, the message network cannot implement real-time snooping. If a broadcasting mechanism is used, a relatively long communication delay may be caused.